The invention relates in general to sonic fusion technology. It relates more particularly to a screw and a method for the fixation of fractures, particularly bone fractures. The invention relates to a screw for augmenting within a fractured object, to a system including tools to implement the screw into the fractured object, as well as to the use of the mentioned system. The fractured object might be a bone or a wooden or plastic object like furniture.
Known from U.S. Pat. No. 4,653,489 is a system wherein a fixation cement is introduced through a screw into a portion of a bone afflicted by osteoporosis. Femoral neck fractures as well as distal femoral fractures can be fixated by means of this device.
The system in accordance with prior art comprises a screw having a flow cavity, i.e. an axial through bore through with bone cement can be introduced into the portion at the tip of the screw. The bone cement is advanced by a device which is releasably attached to the subsequent end of the screw. This device is similar to commercially available syringe, in comprising substantially a cylindrical barrel and a plunger. The barrel forms a cavity in which the plunger is moveable backwards and forwards.
In use of this prior art device, the fixation cement is filled into the barrel, after which the plunger is urged against the cement. By applying manual compression force, the fixation cement is jetted into the axial through bore of the screw. Due to the pressure, the fixation cement is adequately fluidized, so that it can pass through the proximal end of the screw into the bone, as a result of which the screw is augmented in the bone.
This system has the drawback that the manual pressure applied to the fixation cement varies, not only basically from application to application, but also during the application itself, so that the distribution of the fixation cement within the portion of the bone at the tip of the screw is neither reliable nor even.
A device for fixing bone fractures is shown in U.S. Patent Application Publication No. 2009/0018590 the disclosure of which is incorporated herein by reference. A device for applying ultrasonic energy to a screw is shown in U.S. Patent Application Publication No. 2009/0018471 the disclosure of which is incorporated herein by reference. As shown in FIG. 27 of U.S. Pat. No. 7,335,205, use of ultrasonic energy and a polymer pin is known in fracture fixation. The disclosure of U.S. Pat. No. 7,335,205 is incorporated herein by reference.